A novel and efficient method for C–H arylation using well-defined Pd– and Cu–NHC systems has been developed. This process promotes the challenging construction of C–C bonds from arenes or heteroarenes using aryl bromides and chlorides. Mechanistic studies show that [Cu(OH)(NHC)] plays a key role in the C–H activation and is involved in the transmetallation with the Pd–NHC co-catalyst.